Thread drawoff tube construction for open end spinning machines

ABSTRACT

The inner end of the cylindrical passage through the thread drawoff tube flares outwardly toward the fiber collection chamber. The flared portion includes a smooth margin adjacent to the inner tube end and a grooved region spaced from the inner tube end. The grooved region includes equidistantly spaced long longitudinal grooves in the passage surface and intermediate short longitudinal grooves between the divergent end portions of the long grooves. Circumferential grooves in the passage surface intersect the radial plane grooves. In cross section, the grooves have a depth equal to at least one-half of the full diameter of the thread being drawn off. The plane of at least one groove sidewall intersects the principal passage surface at an angle between 45* and 90*.

United States Patent 191 Schuster [451 Apr. 23, 1974 THREAD DRAWOFF TUBECONSTRUCTION FOR OPEN END SPINNING MACHINES [75] Inventor: Friedrichschusterfllainmelburg,

Germany [22] Filed: Aug. 2, 1972 [2]] App]. No.: 277,367

[30] Foreign Application Priority Data Jansen 57/76 Verschragen 57/76Primary Examiner.lohn Petrakes Attorney, Agent, or Firm-Robert W. Beach;Ms. R. M. Van Winkle [5 7] ABSTRACT The inner end of the cylindricalpassage through the thread drawoff tube flares outwardly toward thefiber collection chamber. The flared portion includes a smooth marginadjacent to the inner tube end and a grooved region spaced from theinner tube end. The grooved region includes equidistantly spaced long1ongitudinal grooves in the passage surface and intermediate shortlongitudinal grooves between the divergent end portions of the longgrooves. Circumferential grooves in the passage surface intersect theradial plane grooves. In cross section, the grooves have a depth equalto at least one-half of the fulldiameter of the thread being drawn off.The plane of at least one groove sidewall intersects the principalpassage surface at an angle between 45 and 90.

3 Claims, 4 Drawing Figures Aug. 11, 1971 Germany 2140157 g u.s. q.57/5. 8 9 57 /l 06 [51] Int. Cl D01h 1/12 8] Field of Search 57/58.89,58.95, 34 CP, 57/76, 106

[56] References Cited UNITED STATES PATENTS 3,481,128 12/1969Landwehrkamp et al. 57/58.89 2,052,731 9/1936 Taylor 57/76 THREADDRAWOFF TUBE CONSTRUCTION FOR OPEN END SPINNING MACHINES The presentinvention relates to a thread drawoff tube for an open end spinningdevice which includes a grooved portion in the drawoff passage.

It is well known to toughen the mouth of a drawoff tube passage for anopen end spinning machine, such as by grooves, in order to impart afalse twist to thread drawn through the tube, such as disclosed in SwissPat.

No. 398,395, and French Pat No. 1,468,321. Such construction permitsthread to be drawn off at substantially higher speeds than when thedrawoff passage has a smooth surface.

It is a principal object of the present invention to improve theformation of false twist by the drawoff tube.

Another important object is toenable the drawoff speed to be furthersubstantially increased and thereby to increase the spinning performanceof the machine.

should be of a depth equivalent to at least the radius of the threadbeing drawn through the tube. To prevent interference with rolling ofthe thread from the grooves onto the principal passage surface whileattaining the optimum distribution of false twist imparted to thethread, the sidewall of each longitudinal groove over which the threadmust roll to climb out of the groove is sloped so that the groove wallangle is greater than 45.

FIG. I is a vertical axial section through an open end spinning machinehaving a drawoff tube constructed in accordance with the presentinvention.

FIG. 2 is a bottom plan of the drawoff tube. 7

FIG. 3 is a cross section through a portion of the drawoff tube wallshowing one configuration of a passage. groove, and

FIG. '4 isa similar view showing'a modified groove configuration.

A housing 1 closed by a cover 11 contains a spinning turbine 2 having afiber collection trough24. Fiber is fed to such trough from'a sliver Sby a fiber supply device, shown as feed rolls 5, and a supplytube 51extending through the housingcover. The fiber is drawn as a thread Ffrom the collection trough 24 through a drawoff tube 6 by drawoffrollers3. The thread drawoff tube 6 includes an upper cylindrical passage 63having a lower end portion 60 flared toward the lower. passage mouth.The internal passage surface of .the flared portion 601 has a smoothmargin 600 adjacent to the lower passage mouth and a grooved portion 601above such smooth margin. For spinning of short staple fibers, thethread F is pulled from the collection trough 24 past the smooth margin600 to the grooved portion 60l, where the linear travel of the threadstretch engaged with passage portion 601 is momentarily stopped byfrictional engagement while the trailing thread end continues to rotateso that a false twist is imparted to the thread. The smooth surface 600damps the vibrational effect on the thread created by the change invelocity of the thread portion in the passage, so that such vibration isnot translated to the thread end in the collection trough, whichtransmission might result in separation of the thread end from the fiberin the trough. The smooth damping surface is not necessary for spinninglong staple fibers.

In prior open end spinning devices, the distribution of false twistalong spun thread has been improved by providing a passage portionhaving longitudinal grooves in the passage surface, usually disposed inradial planes. According to the present invention, experiments haveshown that the false twist distribution can be further improved byproviding longitudinal grooves 7 intersected by circumferential grooves70. The combination of intersecting longitudinal grooves 7 andcircumferential grooves permits the thread drawoff speed to be increasedsubstantially, such increase being as great as 50 per cent, depending onthe type of fiber being spun and the rotational speed of the spinningturbine. It is desirable to have the longitudinal grooves approximatelyequally"spaced,. but, because the lower tube portion is flared, thegrooves tend to diverge downwardly. Consequently, shorter longitudinalgrooves 71 are provided between the divergent end portions of grooves 7,as shown in FIG. 2.

Whilethe twist is imparted by the momentary lodging of the threadin thegrooves 7 and 71, such thread portions must again roll circumferentiallyout of the grooves, as indicated, by arrow P in FIG. 3, onto theprincipal surface 6l 'of the passage. Experiments have shown that threadF will roll out of the grooves before excessive tension is placed on thethread pulled in opposition to the restraint of thegrooves if the groovedepth t, indicated in FIG. 3,, is at least one-half the thread diameterd and, preferably, not greater than the full diameter of the spun threadF.

While the depth -t of grooves 7 and 71 determines the ability of thethread to roll out of the grooves in the direction of arrow P onto theprincipal surface 61, the opposingforce tending to hold the thread inthe groove is determined by the groove wall angle or, shown in FIGS. 3and 4. The groove wall angle is the angle between the outwardlyextende'dplane of that groove sidewall over which the thread F rolls outof the-groove and the portion of jsurface 61 adjacent to such wall. Suchgroove wall angle is the supplement of the groove corner angle overwhich the thread rollsout of the groove. The optimum force for holdingthe thread in the groove, and thereby producing a good false twistdistribution, is created when the groove wall angle a is greater than45, and, more particularly, when the angle is between 45 and The grooveconfiguration shown in FIG. 3 is suitable for a spinning machine inwhich the relative rotation of the drawoff tube 6 and the spinningchamber 2 is always in the same direction, so that the circumferentialmovement of the thread F within tube 6 will always be in the directionof arrow P. The groove configuration shown in FIG. 4 permits thetwisting force to be exerted on the thread in either direction becauseboth groove walls form angles a greater than 45. A drawoff tube havingthe groove construction. of FIG. 4 can be used in a'spinning machine inwhich the circumferential rolling force on the thread F is eitherclockwise or counterclockwise.

As indicated by FIGS. 3 and 4, the grooves can have variouscross-sectional shapes and depths, and the spacing between adjacentgrooves may be varied, but the critical minimum depth and range ofangles a must be observed to produce the most efficient machineoperation. The flared tube mouth 60 may also be varied in size andconfiguration without disadvantageously affecting the performance of thetwist-imparting zone 601. The circumferential grooves 70 also may havevarious cross-sectional profiles, but it is preferred that the depth ofsuch grooves be substantially the same as the depth of the grooves 7 and71. While the increased effectiveness of the twist zone 601 created bythe particular improvements described above has been determinedexperimentally, it is probable that these results are produced by theincreased number of thread contact points which exert a greater holdingforce on the thread F. Since the degree of twisting restraint is alsoincreased by steep groove walls, it is preferred that the sidewall angleof grooves 70 be greater than 45, which also sharpens the corners formedby the intersections of grooves 70 with grooves 7 and 71.

It has also been found that a twisting zone formed in accordance withthe present invention will effect good binding of the fiber ring incollection trough 24 to the trailing end of thread F even with a verysmall rotational speed of spinning turbine 2, so that, if desired,spinning can be accomplished at lower speeds than have heretofore beenpractical.

I claim:

1. A thread drawoff tube for open end spinning machines, said tubehaving an inner passage wall, such wall having a grooved thread-engagingsurface, wherein the improvement comprises a plurality of grooves havingtheir lengths extending longitudinally and spaced circumferentially inthe passage wall, and a plurality of longitudinally spacedcircumferential grooves intersecting said longitudinal grooves.

2. The drawoff tube defined in claim 1, in which the depth of eachlongitudinal groove is at least as great as the radius of the threaddrawn through the tube.

3. The drawofi tube defined in claim 1, in which the thread is movablecircumferentially of the tube passage, and the plane of the forwardsidewall of each longitudinal groove in the direction of thread movementintersects the plane of the inner passage wall portion at a groove wallangle greater than 45.

1. A thread drawoff tube for open end spinning machines, said tubehaving an inner passage wall, such wall having a grooved thread-engagingsurface, wherein the improvement comprises a plurality of grooves havingtheir lengths extending longitudinally and spaced circumferentially inthe passage wall, and a plurality of longitudinally spacedcircumferential grooves intersecting said longitudinal grooves.
 2. Thedrawoff tube defined in claim 1, in which the depth of each longitudinalgroove is at least as great as the radius of the thread drawn throughthe tube.
 3. The drawoff tube defined in claim 1, in which the thread ismovable circumferentially of the tube passage, and the plane of theforward sidewall of each longitudinal groove in the direction of threadmovement intersects the plane of the inner passage wall portion at agroove wall angle greater than 45*.